Multiple unit radio tube



Aug. 27, 1940.

A. FEINDEL 2,213,162 MULTIPLE UNIT RADIO TUBE Filed May 23, 1939 2 Sheets-Sheet l INVENTOR A5307? fi m/pa ATTORNEYS 8. 27, 1940- A. FEINDEL 2,213,162

MULTIPLE UNIT RADIO TUBE Filed May 23, 1939 2 Sheets-Sheet 2 INVENTOR 145507-7- FE/NDEL ATTORNEYS Patented Aug. 27, 1940 UNITED STATES MULTIPLE UNIT RADKQ TUBE Application May 23,

8 Claims.

This invention relates to thermionic devices wherein a plurality of units are housed in a single envelope. -More specifically the invention relates to radio tubes of the multiple unit type '5 wherein single elements are associated in common with the various functional units of the tube. In my co-pending application Serial No. 248,981, filed January 3, 1939, I have described a multiple unit radio tube in which a triode and pentode are combined, eachunit performing its usual function but these units have one or more parts in common. These parts are so associated andintegrated that the two units may be placed between common end plates instead of axially end to end without disturbing the electrical characteristics of each unit. H In the present invention I utilize the structure of my co-pending application with an addition oi-a third unit taking the form of a diode, this third unit being associated with the triode by having a common cathode element therewith and being placed accordingly on the same side of the tube as the triode, the pentode being positioned on the other side of the tube.

It is one of the objects of the present invention to provide a specific shield for a diode unit in a multiple unit tube which will permit the employment of an external shield common to all units of the tube. It is another object of the invention to provide a diode shield construction which will facilitate the conversion of the oxide coating of the-cathode of the diode during the manufacturing process. It is a further object of the invention to so associate and combine the various elements of a combination diode, triode and pentode units so as to bring about a mechanical integration without disturbing the individual-electrical characteristics of each unit. Further objects pertaining to the details of construction and the process of manufacture will become apparent on consideration of the modification of the invention which may be pre ferred hereinbelow described and illustrated in the accompanying drawings, in which:

Fig. 1 is an elevation of the completed tube;

Fig. 2 is' a vertical section of the tube along lines 22 of Fig. 1, showing the pentode unit;

Fig. 3 is an elevational detail showing the diode-triode side of the tube;

Fig. 4 is a vertical sectional detail showing the diode, triode and pentode units;

Fig. 5 is a plan section on lines 5-5 of Fig. 4;

Fig. 6 is a plan section on lines 56 of Fig. 4;

Fig. 7 shows the preferred base electrical connections; and

1939, Serial No. 275,137

(or. est- 27.5)

Fig. 8 shows modified base electrical connections.

The radio tube 58 has a glass casing I! having at its base a shell l2 of metal or other material, insulation base plate i3, and terminals it. At the other end of the tube is the metal cap i5 forming the terminal of the control grid, as will hereinafter be described. As shown in Fig. 2, the base plate i3 is notched at spaced points around its periphery and provided with angular projections it adapted to engage turned-in pore tions ll of the shell base so that these two parts are held rigidly together. The plate i3 is also provided with a series of circumferentially placed apertures it which are adapted to receive the ends of the terminals i l. The plate !3 is also formed with a downwardly extending well is which is adapted to receive the exhaust tube "Rt of the envelope.

Within the glass envelope ii a press 25 is formed to receive the various support rods 22 and 23, as well as the various lead in wires 25, 25, 26, 27, 2Q, 30, 3E, 32 and 33 and the filament support wires 28 and (it. The various units of the tube are supportedprimarilyon the standards 22 and 23 which extend from the stem 26 up to a point in proximity to the top end of the tube as opposed to the base end. Base and top mica plates, numbered respectively 35 and and apertured to receive the various support rods 22 and 23, as well as the various element support rods of the electrical units, are employed to position the elements in place in the envelope. Mica plate 35 is supported on rods 22 and 23 by the attached strips 86, and mica plate 35 rests on the upper edge of shield 33, hereinafter described. These mica plates are somewhat'elongated in shape and are provided at the ends with projecting prongs 3! normally adapted-to contact with the interior surface of the glass envelope and hold the multiple unit in fixed position relative thereto.

Along the axis of elongation of the mica plates and between the same is placed the flat imperforate metal shield 38, attachment being made by welding the ends of the shield grooves 39 to the support rods 22 and 23 lying within said grooves. The outer edges of the plate are turned oppositely to form circumferentially flattened surfaces 453 which areadapted to engage and support the cylindrical shield ll enclosing the entire multiple unit. The shield M is perforated and encloses approximately the entire space between the mica plates.

It will thus be seen that the perforated screen shield M, in conjunction with the central imperforate shield 38 and the base and upper mica plates, divides the shield interior into two compartments. One of these compartments is adapted for reception of the pentode unit, as shown in Figs. 2 and 4 and designated generally by the letter A, the other compartment being adapted to contain the triode unit designated by the letter B, and the diode unit designated by the letter C.

The construction of pentode A follows ordinary practice in that there is disclosed a cathode "5 coated with electron emitting material and heated by a double hairpin filament 46. The ends of the cathode pass through and are supported by the mica plates 35 and 36. Surrounding the cathode is the control grid i'l wound on support rods 48 and 49, the rod 49 being extended into the space above the upper mica plate 36 where connection is made through the lead-in wire 5!] to the grid cap [5 on the top exterior of the tube. grid 52 supported by support rods 53 and 5d, the suppressor grid 55 supported by support rods 5'5 and 51, and the anode 58 supported on sup port rods 59 and 60. It is pointed out that the ends of the cathode and the various grid and plate support rods extend through and above the upper mica plate 36.

Unit B is illustrated as a triode unit including the cathode BI extending through the upper mica plate 36 and the lower mica plate 35, extending through and heated by the hairpin filament (i2. Surrounding the triode cathode is the control grid 63 mounted on the support rods 66 and 85. It is pointed out that the support rods 64 and 65 do not extend to the base mica plate 35 but terminate above the same, being held at their base ends by a third mica plate 66, which in turn is supported by U-shaped members 5? welded or otherwise attached to the anode support rods 68 and 63. The anode 1B surrounds the grid 83 and is supported by the anode support rods 68 and 69.

The space formed between mica plates 66 and 35 is utilized for the diode unit C. This unit includes the cathode 61 which extends through the plate 36 and a cylindrical anode ll which surrounds the cathode and is supported by rod 72 extending through the plate 35. To protect the diode unit from electrostatic and electromagnetic effects from the adjacent triode, use is made of an imperforate metal shield 13, roughly L -shaped, with the base portion Til of the U perforated to receive the cathode SI, and the end sections 15 of the U positioned adjacent two sides of the diode, the base of the U being above the diode unit and the side ends fastened to the base mica plate 35. As shown in Fig. 4, the U- shaped shield 73 is so positioned that one open side is adjacent the shield 38 of the tube, and the other open side is adjacent the perforated cylindrical screen shield M. It will thus be seen that the diode unit is effectively enclosed, all walls being metallic except the mica plate at the base of the unit. It is further apparent that because of the open side adjacent the shield ll it is possible to aid the normal conversion of the cathode coating material by radiating heat to the diode unit from the shield 4! which is heated by induction during manufacture. It is further pointed out that because of the simplicity of the diode shield !3 the same may be readily constructed and placed in position.

As is well known in this art, the extension of the control grid of the pentode in the support Surrounding the control grid is the screen rod 49 and lead-in connection above the plate 36 and in proximity to the ends of the triode support rods brings about, unless corrected, certain electrostatic and electromagnetic interaction. In order to avoid this interaction and permit the association of the pentode and triode units in parallel relationship with each other, I utilize a metal shield 16 consisting of a base plate ll having a depending wall 18, the edge of which is adapted to seat within the upper end of the perforated shield 4|. Portions of the wall on opposite sides are cut away to form a Window for the extension of the prongs 31 on the ends of the mica plate 36. The ends of the main support rods 22 and 23 extend through the base '1'! of the shield E5, the metal parts thereof being rip-turned and welded to the support rods for retaining the shield in position. In the area overlying the grid support rods and cathode of the pentode unit the shield metal is turned downwardly to form a rectangular cavity with closed side and end walls, in which cavity the grid terminals extend. It will thus be seen that the control grid support rods, as well as the other grid support rods of the pentode, are metallically shielded from the support rods of the triode and the various elements thereof, thereby insuring elimination of inter-unit electrostatic and electromagnetic effects.

In Fig. 7 I have illustrated a suitable wiring diagram showing the connections between the base terminals, the shields, and the elements of the various units. From this diagram it is apparent that the combined shield 38-4l is utilized in conjunction with all three units, and further, that the cathode 6! forms a part of the unit construction of both the triode and diode units. In this manner the multiple construction is integrated to the parts or elements and the whole construction simplified. By this construction also is made possible the association of the diode and triode in a space not in elongation with but in parallel relationship with the pentode between the mica plates and 36, thereby permitting additional compactness and simplification in arrangement.

Fig. 8 illustrates a modified method of connecting the various unit elements to the terminals.

Modifications other than those hereinabove bed may be made provided they come wit -n the scope of the claims hereto appended.

I claim as my invention:

1. A thermionic device comprising plural thermionic units including an amplifying unit, a common base for said units, a common envelope enclosing said units a stem extending from said base, main support rods and lead-in wires projecting from said stem into the envelope, a cylindrical shield mounted on said main support rods, mica end plates at the end of saidcylindrical shield a flat metal shield bridging said main support rods and dividing the cylindrical shield into two compartments, a thermionic unit including a heater, a cathode, a grid and an anode mounted on support rods within each compartment, some of the ends of the support rods proof the adjacent thermionic unit, a U-shaped shield positioned with its surface vertical to the flat shield and enclosing the anode on the upper and lateral sides, and a top shield forming a common closure for the outer ends of said units, said top shield comprising a plate having an edge flange and struck-out portions forming an opening in the plate surface with depending side and end walls adapted to overlie the thermionic elements of one of said units and enclose the protruding ends or the support rods of said elements whereby the inter-unit electrostatic and electromagnetic efiects effectively reduced.

2. A thermionic tube comprising a base having external terminals therein, an envelope mounted on base, a reentrant stem within said envelope, lead-in wires and main support rods mounted on said stem, a flat metal shield extending between said support rods, a metal cylinder enclosing said shield, two thermionic units within one of the compartments formed between the cylinder and shield, a third thermionic unit in the other of said compartments, insulation plates at each end of, said thermionic units provided with apertures and projecting prongs to form support and spacing means for the elements of said units, a U-shaped shield overlying one unit in the two unit compartment, and a metal shield plate overlying the outer ends of the thermionic units, said end plate having depending walls completely enclosing the end portions of the elements of one of said units.

3. A thermionic device comprising a base, electrode terminals mounted in said base, an envelope mounted on said base, a stem within said envelope, main support rods extending from said stem, a metal shield extending between said main support rods, a cylinder enclosing said shield and forming dual chambers, a thermionic unit including heater, cathode, grid and anode elements mounted in each of said chambers, a thermionic unit including heater, cathode and anode in one of said chambers, support rods for each of the elements of said units, insulation plates overlying each unit of the shield cylinder, said plates having apertures adapted to receive 1e protruding ends of the elements of said units, a U-shaped shield interposed between the two thermionic units contained in. a single chainber, and a metal plate overlying the insulation plate at the end of the tube opposite from the base, said end plate having a struck-out portion with depending walls forming a closure for the protruding ends of the element supports of one of said units, and means for connecting the control grid of said support rod ends enclosed unit to a terminal other than the base terminals.

4. A thermionic device comprising an elongated envelope, a base at one end of the envelope, wire terminals in said base, a stem in the base end of the envelope, main support rods and lead-in wires mounted on said stem, a plate joining said main supports, thermionic units containing grid elements mounted one on each side of the plate, a cylindrical shield surrounding said units and plate, a top shield overlying the ends of both units, said top shield having depending sections enclosing the end of the grid element of one of said units, a third thermionic unit on one side of said plate, and a U-shaped metal shield between said third unit and the adjacent thermionic unit.

5. A radio tube comprising multiple thermionic units including a diode, a triode and a pentode, a common envelope and base for said units, and a common shielding means for said units, said means including a metal casing adapted to receive said units, a metal plate interposed between the pentode and the diode and triode, and a metal end plate at the top end of said casing, and an additional shield interposed between said diode and triode, said additional shield being U-shaped with the open sides adjacent the metal plate and metal casing respectively, and the base at the top of the diode.

6. A thermionic device comprising an envelope, a stem support therein, main support rods mounted on said stem, a fiat metal plate between said rods, a perforated metal cylinder enclosing said plate forming dual compartments, insulation strips at either end of said cylinder, a thermionic unit in one of said compartments, two thermionic and axially positioned units in the other of said compartments, a third insulation strip interposed between the last named two thermionic units, and separate metal shields overlying each of said two thermionic units, one of said shields also partially overlying the thermionic unit in the other of said compartments.

7. A radio tube comprising three thermionic units having support rods therefor, an insulation plate adapted to receive said support rods, a flat metal plate interposed between two of said units and the third unit, a U-shaped metal plate interposed between two oi": said units, and a common external shield for all of said units.

8. A radio tube comprising three thermionic units having support rods therefor, an insulation plate adapted to receive said support rods, a fiat metal plate interposed between two of said units and the third unit, a U-shaped metal plate interposed between two of said units, and a common external shield for all of said units, said U-shaped metal plate having its surface perpendicular to, and its edges in approximate engagement with, said insulation.

ABBOTT FEIN'DEL. 

